Atrial Fibrosis and Atrial Fibrillation: A Computer Simulation in the Posterior Left Atrium

摘要

Computer models, especially those integrated with high resolution 3D surface geometry and myofibre structure throughout the whole atria, are powerful instruments to investigate the mechanism of atrial fibrillation. There are many factors that may contribute to electrical instability of the posterior left atrium (PLA): 1) abrupt changes in wall thickness and myofiber orientations of PLA, 2) different action potential duration in pulmonary vein sleeves and adjacent left atrium (LA) and 3) fibrosis patch. The first two factors have been investigated in our previous work. Here, we further develop an image-based atrial model by incorporating computer-generated fibrosis into the LA to reflect the structure remodeling, motivated by the fibrosis imaging data from Utah. A novel compact finite difference method was implemented to solve the governing cardiac equations. A bursting simulation protocol was applied in the PLA with different levels of structure remodeling and control. Marked conduction delays and uni-directional block were seen with both anisotropy and structure remodeling. The existence of fibrosis increases regional electrophysiological discrepancies and chance of uni-directional block. We conclude that existence of fibrosis potentially increase the occurrences of conduction reentry and the number of wavelets, contributing further to electrical instability in PLA.